This invention relates generally to a method and apparatus for providing lubricating oil in an internal combustion engine and, more particularly, to a method and apparatus for using portions of a gear train located in an internal combustion engine to pump lubricating oil.
Internal combustion engines require lubricating oil at various locations to lubricate moving components, remove heat generated by the movement of the components, and remove particles created by the components in contact with each other. Typically, the oil is delivered to the desired locations by the use of oil pumps. Oil pumps may be any one of several types, but a very common method is to use engaging gears which gather oil into the gear teeth and then pump the oil under pressure as the teeth mesh together and rapidly push the oil out from between the teeth.
Attempts have been made in the past to use gears which exist for other purposes rather than use gears dedicated for pumping oil and located within an oil pump body. For example, attempts have been made to use a crankshaft gear in combination with a camshaft gear to pump oil as the gear teeth mesh.
U.S. Pat. No. 1,083,329, issued to Lancia, depicts one of the first known attempts to use crankshaft and camshaft gears as oil pump gears. The oil enters a sealed chamber at the location in which the gear teeth separate, travel between the teeth for a complete revolution of the gears, and exits under pressure at the location in which the teeth mesh together. A variation of this same principle is found in U.S. Pat. No. 2,883,001, issued to Dierksen.
In U.S. Pat. No. 1,585,731, Oakes discloses another variation in which oil enters at the location in which the teeth of the crankshaft and camshaft gears separate, thus providing a first aspect of an oil pump. Oil also enters at the location in which the teeth of the camshaft gear separates from the teeth of a generator gear, thus providing a second aspect of the oil pump. The total travel path of the oil includes a complete revolution of the camshaft gear, as well as complete revolutions of the crankshaft and generator gears.
In the examples described above, oil must travel virtually all the way around the gears being used. This requires that the gears be located in sealed chambers to prevent oil from leaking. Another disadvantage is that not all of the oil remains between the gear teeth during travel of the gears, thus reducing the amount of oil remaining between the teeth as they mesh. This in turn reduces the amount of oil available to be pumped to the desired parts of the engine.
The present invention is directed to overcoming one or more of the problems as set forth above.
In one aspect of the present invention an apparatus for pumping oil in a machine is disclosed. The apparatus includes a first gear drivably connected to the machine, a second gear connected to the machine such that a set of teeth located on the first gear engage a set of teeth located on the second gear, an oil inlet port located near the teeth of the first gear slightly before a point of engagement of the teeth of the first and second gears, and an oil outlet port located at the point of engagement of the teeth of the first and second gears.
In another aspect of the present invention a method for pumping oil in a machine is disclosed. The method includes the steps of providing a supply of oil to a set of teeth of a first gear drivably connected to the machine at a location slightly before a point of engagement of the teeth of the first gear with a set of teeth of a second gear, transporting the oil between the teeth of the first gear up to the point of engagement, and pumping the oil to a desired location in the machine as a function of engagement of the teeth of the first and second gears.